1. Field of the Invention
The invention relates to a process and apparatus for printing of print carriers and, more particularly, a rotating body supported in rotating fashion with a printing form, mounted on a body surface facing a print carrier and supported on a stand. The invention particularly relates to printing on print carriers in an offset printing machine with one or more printing units, each comprising a printing form and a transfer cylinder, together with a dampening system and an inking system, wherein the printing form is provided with process specific functional layers, i.e. one water and one ink absorbing layer.
2. Description of the Related Technology
In offset printing processes, plates mounted on carrier cylinders fixedly installed in a printing unit are used. Clamping segments extended through the carrier cylinder are used to mount the plates. The plates begin and end within the extent of these clamping segments, accordingly the print carrier location corresponding to an end or a beginning of the printing form is recognizable. It has not previously been possible to produce endless images with printing forms of this type due to the configuration of the printing form. Furthermore, this layout permits only relatively low rotating velocities. The carrier cylinder did not have a symmetrical or balanced configuration. High vibratory stresses are generated in the printing unit by operation of unbalanced cylinders. The unsymmetrical shape of carrier cylinders limits the permissible web widths. In addition, the carrier cylinders were heavy and required very carefully designed bearing supports in the printing units. The machines were therefore expensive.
For endless printing heretofore only gravure printing and the flexoprint process could be used. The flexoprint method only enabled small, narrow formats to be printed in small volumes and with an inferior quality. The gravure process requires smooth, flat print carriers. In numerous cases the gravure printing process is not optimally suited for applications involving the production of high quality endless prints. In particular, the gravure process is not applicable to the printing of laminated papers, wallpapers and gift wrappings. Furthermore, the gravure process is very expensive and time consuming with respect to the preparation of the printing forms required, as the printing forms must be inserted directly into a gravure cylinder. The expensive gravure cylinders must be available in adequately equipped printing establishments in relatively large numbers.